BASTAD, Sweden -- Moroccan second seed Younes el Aynaoui struggled to beat Germany's Lars Burgsmuller 6-3 4-6 7-5 in the first round of the Bastad tournament on Monday.

Seventh-seed Mariano Zabaleta also progressed in the $400,000 claycourt event after a tough encounter with Sweden's 18-year-old wildcard Robin Soderling.

The Argentine eventually won 7-6 7-6 after two close tiebreaks, while Chile's Fernando Gonzalez, seeded sixth, beat the other Swedish wildcard Magnus Larsson 7-5 6-3, Reuters reported.

Argentina's Augustin Calleri produced the only upset of the day by beating Finnish fifth seed Jarkko Nieminen 6-1 6-4.

In an all-Spanish encounter, Albert Portas beat Fernando Vicente 4-6 6-4 6-4, while Czech Bohdan Ulihrach disposed of American Vincent Spadea 6-3 6-1.